Technical Field
The present disclosure relates generally to a surgical fastening instrument for applying surgical fasteners to body tissue. More particularly, the present disclosure relates to a surgical fastening instrument that is locked out from firing fasteners until the cartridge assembly and anvil assembly are sufficiently approximated.
Background of Related Art
Anastomosis is the surgical joining of separate hollow organ sections. Typically, an anastomosis procedure follows surgery in which a diseased or defective section of hollow tissue is removed and the remaining end sections are to be joined. Depending on the desired anastomosis procedure, the end sections may be joined by either circular, end-to-end or side-to-side organ reconstruction methods.
In a circular anastomosis procedure, the two ends of the organ sections are joined by means of a stapling instrument which drives a circular array of staples or fasteners through the end section of each organ section and simultaneously cores any tissue interior of the driven circular array of staples to free the tubular passage. Examples of instruments for performing circular anastomosis of hollow organs are described for example in U.S. Pat. Nos. 7,303,106, 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745, 4,576,167, and 4,473,077, each of which is incorporated herein in its entirety by reference. Typically, these instruments include an elongated shaft having a handle portion at a proximal end to actuate the instrument and a staple holding component disposed at a distal end. An anvil assembly including an anvil rod with an attached anvil head is mounted to the distal end of the instrument adjacent the staple holding component. Opposed end portions of tissue of the hollow organ(s) to be stapled are clamped between the anvil head and the staple holding component as these components are approximated. The clamped tissue is stapled by actuation of a trigger to drive one or more staples from the staple holding component so that the ends of the staples pass through the tissue and are deformed by the anvil head. An annular knife is concurrently advanced to core tissue within the hollow organ to free a tubular passage within the organ.
Besides anastomosis of hollow organs, surgical stapling instruments for performing circular anastomosis have been used to treat internal hemorrhoids in the rectum. Typically, during use of a circular stapling instrument for hemorrhoid treatment, the anvil head and the staple holding component of the surgical stapling instrument are inserted through the anus and into the rectum with the anvil head and the staple holding component in an open or unapproximated position. Thereafter, a pursestring suture is used to pull the internal hemorrhoidal tissue towards the anvil rod. Next, the anvil head and the staple holding component are approximated to clamp the hemorrhoid tissue between the anvil head and the staple holding component. The stapling instrument is fired to remove the hemorrhoidal tissue and staple the cut tissue. In stapled hemorrhoidopexy, a strip of mucosa and submucosa at the top of the hemorrhoids is removed by the stapling instrument, thereby treating the hemorrhoids by inhibiting blood flow to the tissue.
In certain situations, it is desirable to prevent premature firing of staples. Accordingly, it would be desirable for a surgical instrument to include a lockout mechanism that prevents the movable handle from being actuated until the anvil assembly and the cartridge assembly are sufficiently approximated.